Possibly bricked, request for help with Archer C6

[bembis]

Good evening, I have recently decided to try OpenWRT thinking it would be relatively easy, especially since I have previous experience with Linux servers and whatnot, so it came in handy. The decision was because I noticed I sometimes face some odd packet loss in certain applications despite having very stable internet connection, furthermore, I had quite a lot of trouble with running servers and setting up port triggering for quite some time, so I wanted to try this out and see the difference.

I proceeded flashing the image in the router's page here, used version 19.07.5, however after flashing, I had no internet access. I had no idea why, it was my first time, I tried researching in various forums and trying to find someone that could actually help, but to no avail. I suppose it was related to an improper configuration because usually you need to set it up for your specific case - I have no idea what is my case.

I have 1Gbit internet that comes to my flat with an optical fiber cable, which runs to a fiber converter that has one Ethernet port. From the converter, the Ethernet cable runs to the Archer C6 v2 router WAN port. From here, I just have an Ethernet cable run to my PC from the first LAN port of the router. I have a dynamic IP address, meaning that usually after restarting the router, I receive a new IP address. As far as I understand, my router uses DHCP, at least it was configured to do so in official firmware, which is what the openWRT image is also configured to do - however, it didn't work, and soon for two days I will be sitting here without internet access.

I had no idea how to set this up in Interfaces, because that's where I thought the problem lies. Whenever I tried to edit some settings on the lan interface, it would often fail to apply and try to rollback, which would just stay there indefinitely, I would refresh the page and revert the changes (unless it refused to do so and I had to re-flash using TFTP).

After this, I realized I am not up to the task and I have no skills to make this work, nor knowledge. I got official firmware from TP-LINK website (1.3.5), flashed it using OpenWRT web GUI, but it kept on saying that it will upgrade and never restarted or actually flashed properly. I left it overnight because it was 7AM already (over-day really), and have been trying to fix it for the whole day today.

Let me tell you this - even if I flash the file using TFTP (turn off router -> hold RESET -> turn on router), the router does seem to grab the file from my PC, however, it just restarts and all I see is a glowing power LED. From there on, I tried to flash these official firmware versions: 1.0.1, 1.3.4, 1.3.5, 1.3.6 and two stripped bins that I found in the forums with no avail. FURTHERMORE, if I flash using TFTP when openWRT is flashed and accessible, it simply grabs the file, and then continues to reboot normally to openWRT and doesn't flash the firmware.

The only image that ACTUALLY FLASHES is ONLY openWRT. I have no idea why and don't understand why (and can't find any information about this, which infuriates me), but whenever I flash the official firmware with the web GUI or with TFTP, it never flashes I assume, and the only firmware that now flashes is only openWRT, which means I am basically stuck without internet access and with no way to revert back to original firmware.

I request help for fixing this, I am completely broken and tired with no more choices left.

Current configuration in the Interfaces of web GUI:

[bembis]

After countless bins, I have flashed the .bin file that was provided in here, using that, for some reason, allowed me to flash from web GUI without a problem. I also met one single person who had the same issue and couldn't revert to stock firmware, so the individual stayed on openWRT for the rest of the time, so I informed him of that as well in case he needs it in the future.

It could be a very rare issue because the person in the linked thread wasn't able to flash stock firmware either.

I still haven't found a way to configure my interfaces for internet access with DHCP, but I was able to revert to stock firmware. If I manage to find a way to fix the internet access or find someone to help me, I will update this post with instructions.

[johnfzc]

OpenWrt should have worked the same as your existing firmware, at least in regards to default DHCP on the WAN interface. I thought your issue may have been caused by a change in MAC address, which can sometimes happen on specific router models. As you have reverted to stock and are still having issues I think you should contact your ISP and ask them to confirm what your WAN configuration should be and have them troubleshoot what they see on their end of the connection.

[bembis]

Thanks for the reply. To clear things up, the stock firmware that I flashed after everything I had tried, actually has internet access and functions absolutely fine. The only problem I had with was openWRT that didn't work for me - I couldn't access internet in any kind of way.
The configuration did seem to be correct to my unexperienced eye, but I have never used openWRT before, so I had no idea how to deal with it. I would like to try again but I'd only do so when I had understood and found enough information to experiment with after flashing openWRT once again, because I need internet quite often and I can't have very long down-time due to complicated configuration (which is probably due to my incompetence).

[johnfzc]

Hmm, it's not clear to me why the stock firmware is functioning and OpenWrt is not, I would guess the most likely reason is that the MAC address used for the WAN isn't the same between the two firmware's, this is the only configuration I can think of that could be different from one firmware to the other that would be present in a default DHCP configuration.

You could, if you wanted to, see if you can view the MAC address associated with the WAN interface in the stock firmware and then flash OpenWrt and validate and possibly override the WAN mac address to make it match with OpenWrt. This may be more trouble than it's worth for you though.

[bembis]

I did check the MAC address, it seems identical to the stock firmware. I still force-replaced it just in case, but that didn't do a thing.
I also put stock DNS server IPs to the LAN interface, but that didn't do the trick either. I set the same IPs as much as I could do, including IPv4 gateway and all that. None of those things helped, unfortunately. Perhaps I am doing something wrong though, it could be that.

[johnfzc]

I don't understand why it didn't work, but can't suggest anything you could try to fix it.

It would be interesting to connect a pc to the wan port and packet capture the port to see if you see the DHCP requests coming out the port, it may be that the WAN port is somehow incorrectly configured in 19.07.

If you see the traffic you could also capture it from the stock firmware, if you provide us with both captures we may be able to spot a difference.